The present invention relates to a liquid crystal display (LCD) device. Especially, the present invention relates to a LCD device or unit having a LCD panel in which a so-called edge-light type back light system is employed, the back light system having a fluorescent tube placed close to and along one side of a light guide, and in which a lamp reflector is provided which extends almost the whole length of the fluorescent tube.
A liquid crystal display unit of the type mentioned above includes, for example, a liquid crystal display (i.e., a liquid crystal panel, LCD: Liquid Crystal Display), a back light mounted under the liquid crystal display for supplying light thereto, a liquid-crystal driving circuit board disposed outside the outer periphery of the liquid crystal display, a frame body in the form of a molded part for holding each of the above members, and a metal frame for accommodating these members, the metal frame being provided with a display window. The liquid crystal display is typically prepared by stacking two transparent glass substrates with a predetermined spacing in such a manner as to cause display pixel electrodes, formed with a transparent conductive film, to face an orientation film, sticking the two glass substrates together using a frame-shaped sealing material placed close to the peripheral edge between both substrates, feeding liquid crystals through a liquid crystal sealing port provided in part of the sealing material to enclose the liquid crystals in the sealing material between both substrates, and providing polarization plates outside the substrates.
The back light comprises, for example, a light guide formed of a transparent acrylic plastic plate for guiding the light emitted from a light source in a direction away from the light source for irradiating the whole liquid crystal display uniformly with light, a fluorescent tube placed close to, along and in parallel to one side of the light guide, a lamp reflector covering substantially the whole length of the fluorescent tube, the lamp reflector being substantially U-shaped in cross section and having an inner face which is colored white or silver, a diffusion sheet disposed on the light guide for diffusing the light from the light guide, and a reflective sheet for reflecting the light from the light guide toward the liquid crystal display.
Moreover, the light emitted from the fluorescent tube is introduced into the light guide where it is subjected to total reflection. In order to cause the light to be sent from the top surface of the light guide by means of diffused reflection, however, there is formed a pattern of a plurality of light diffusion dots printed with white ink on the bottom surface of the light guide, or well-regulated protrusions or recesses are incorporated in the bottom surface of the light guide.
Such conventional liquid crystal display units have been described in, for example, Japanese Patent Publication No. 19474/1985 and Japanese Utility Model Unexamined Publication No. 22780/1992.
FIG. 17A is a top view of a conventional liquid crystal display unit (module), and FIG. 17B is a top view of the latest liquid crystal display unit, wherein reference numeral 63 denotes a liquid crystal display module; 41 denotes a metal frame (i.e., shielding case); 80 denotes a display window; and 62 denotes a liquid crystal display.
FIG. 18 is a view of a fluorescent tube in combination with a light guide, wherein reference numeral 36 denotes a fluorescent tube; 37 denotes a light guide; 65 denotes a light-receiving edge face; and 81 denotes a light leakage zone.